Apply a function to column vectors in array.
Applies the given function fcn to each column vector in the array x, by iterating over the indexes along all dimensions except dimension 1. Collects the function return values in an output array.
fcn must be a function which takes a column vector and returns a column vector of the same size. It does not have to return the same type as x.
Returns the result of applying fcn to each column in x, all concatenated together in the same shape as x.